FTD-RRB-NTPC (CBT-I) EXPLANATIONS - 12.01.2025

Sep 5, 2026

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Answer keys and detailed explanations for CBT-I style multiple-choice questions, covering topics such as mirror-image reasoning, coded word/letter patterns, numeric relationships, HCF/LCM-based problems, percentage and ratio calculations, sequence completion, and assumption-based reasoning. Includes step-by-step logic for selecting the correct option, including algebraic transformations, number-theory derivations, and interpretation of statements. Designed for revision and performance improvement through solution breakdowns.

LanguageEnglish

CategoryExam

FormatPDF

Pages6

Reading Time15 min

AccessFree to download

ANSWER KEYS

EXPLANATIONS

Solution steps by question number

ANSWER KEYS 1 c 26 b 51 d 76 b 2 d 27 c 52 c 77 c 3 c 28 c 53 a 78 c 4 b 29 b 54 c 79 b 5 a 30 d 55 a 80 b 6 a 31 d 56 a 81 b 7 b 32 c 57 c 82 d 8 d 33 d 58 b 83 a 9 c 34 a 59 c 84 d 10 c 35 d 60 a 85 b 11 a 36 b 61 c 86 c 12 c 37 c 62 a 87 d 13 b 38 c 63 d 88 b 14 b 39 a 64 b 89 c 15 b 40 b 65 a 90 d 16 b 41 d 66 d 91 b 17 c 42 a 67 b 92 c 18 c 43 c 68 b 93 a 19 d 44 d 69 c 94 b 20 c 45 d 70 d 95 d 21 b 46 b 71 b 96 c 22 c 47 d 72 a 97 c 23 c 48 d 73 b 98 a 24 a 49 d 74 c 99 d 25 c 50 c 75 c 100 a EXPLANATIONS 1. c 2. d 3. c 4. b 5. a 6. a; The correct mirror image is given in option IV. 7. b; Only conclusion II follows 8. d; | T | E | M | P | E | R | A | T | U | R | E | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | 1st, 2nd, 4th, 6th, 9th, letters are T, E, P, R, USo, the meaningful word formed is ERUPT. So, the first letter from the left end is E. 9. c; B was taller than only 2 other persons: > >B > > C was taller than B but shorter than A: A > C > B> > D was not the shortest: Thus, the final sequence is as follows: A > C > B > D > E 10. c; Their codes are: Wonder shine little= prqgqpsnt Shine fine gone= klpmonsnt Fine little hit= nokklpgqp, Shine=snt, Fine=klp, gone=mon Hence, option 3. 11. a; 3000 = 3 × 1000 = 3 × 103 Clearly, when we divided 3000 by natural number 3, the quotient is 1000 which is a perfect cube. 12. c; 0.142857􀁹 0 .285714 142857 285714 112857 1 = 􀁹 = = 999999 999999 285714 2 13. b; 2 = 1.414(Given) Now, 2 −1 = (2 −1)2 2 + 1 2 −1 = (2 −1)2 = 2 −1 2 + 1 = 1.414 = 0.414 14. b; 1(.70535 + 􀀾0.75 + (0 .75)2 􀁵1+ 1􀁀= (0 .75)3 + (1− 0 .75)􀀾(0 .75)2 + 0 .75􀁵1+ 12 􀁀 1− 0 .75 (0 75)3 + 13 − (0 75)3 1 100 = ~~ ~~.~~ ~~.~~ ~~ = ~~ ~~ = ~~ ~~ = 4 0.25 0.25 25 15. b; The least number of 5 digits = 10000 243 41 10000 82 | 180
164 | | --- | | 160
123 | 37 Required number = 10000 + (41-37) = 10004 16. b 17. c 18. c 19. d 20. c 21. b; C5C6=C1≤C4=C3 C3≥C1 is true C6≥C4 is false Hence option 2 is the answer 22. c; 7 6 3 1 2 6 4 8 2 7 9 5 3 1 8 4 9 5 7 1 4 8 5 6 9 2 3 There are two such 2's which are followed by a number greater than 5. (23-25) 23. c; 24. a; 25. c; 26. b; HCF of two numbers = 27 Let the numbers be 27x and 27y where x and yare prime to each other. According to the question, 27x + 27y = 216 Possible pairs of x and y = (1, 7) and (3, 5) 27. c; Let the numbers be 17x and 17y where x andy are co primes LCM of 17x and 17y = 17xy According to the question 17xy = 714 Or, x = 7, y = 6 First number = 17x = 17 × 6 = 102 Second number = 17y = 17 × 7 = 119 Sum of the numbers = 102 + 119 = 221 28. c; Required percentage = 29. b; Let Rama’s expenditure = Rs 5x Savings = Rs 3x Rama’s income = 5x + 3x = Rs 8x After increase, Rama’s income = Rama’s expenditure = Rama’s savings = Rs (8 .96 x – 5 .75x) = Rs 3. 21x Rama’s saving percent = 30. d; Last number = 30 × 12 –(20 × 11 +9 × 10)= 360 –(220 + 90) = 360 – 310 = 50 31. d 32. c 33. d 34. a 35. d 36. b; | B | E | N | C | H | M | A | R | K | S | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | 2 | 5 | 14 | 3 | 8 | 13 | 1 | 18 | 11 | 19 | The pairs are: EC, EH Hence 2 such pairs. 37. c; If we take the position values of the alphabets where A=1, B=2 and so on till Z=26 then the position value of 1st alphabet is 3 more than the position value of the 2nd alphabet. E(5) B(2) J(10) G(7) K(11) N(14) R(18) O(15) 38. c; Therefore, the missing term should be 80. Hence, option C is the correct answer. 39. a; The equation will be: 21÷3x12+9=93 7x12+9=93 84+9= 93 Hence, option A is the correct answer 40. b; In statement number of cases of alcohol poisoning are referred not the extent of alcohol consumption. Thus, assumption I is not implicit. Statement indicates that in rural areas low

FAQs

What sections are included in the document?

The document contains an ANSWER KEYS section followed by an EXPLANATIONS section with step-by-step solution notes for each question.

How are the correct options determined in the explanations?

Each explanation applies the relevant method (e.g., algebra, number theory, coding/pattern rules, ratios/percentages, or logical inference) and shows how the computed result matches the stated correct choice.

Which types of questions are covered?

The content includes reasoning problems like mirror-image and assumption-based questions, pattern/coding letter tasks, and quantitative problems involving sequences, HCF/LCM, ratios, and percentages.

Sep 5, 2026

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